Medicare beneficiaries don't have to do anything differently and will continue to go to Medicare.gov to sign up for plans. But advocates say many have been confused by a massive media blitz directing consumers to new online insurance exchanges set up as part of the federal health law. Many of the same insurance companies are offering coverage for Medicare and the exchanges.

Medicare open enrollment starts Oct. 15 and closes Dec. 7, while enrollment for the new state exchanges for people 65 and under launches Oct. 1 and runs through March.

"Most seniors are not at all informed. Most seniors worry they're going to lose their health coverage because of the law," said Dr. Chris Lillis, a primary care physician in Fredericksburg, Virginia. "I try to speak truth from the exam room but I think sometimes fear dominates."

Next month, roughly 50 million Medicare beneficiaries will get a handbook in the mail with a prominent Q&A that stresses Medicare benefits aren't changing. Federal health officials have also updated their training for Medicare counselors, and are prepping their Medicare call center and website.

"We want to reassure Medicare beneficiaries that they are already covered, their benefits aren't changing, and the marketplace doesn't require them to do anything different," said Julie Bataille, spokeswoman for the Centers for Medicare and Medicaid Services.

But she said call centers for the state exchanges are already fielding questions from Medicare recipients and rerouting them to the Medicare line.

Bob Roza attended several meetings trying to figure out exactly what the Affordable Care Act means for him and his 69-year-old wife Gail, who has diabetes.

"At that time, I didn't know if Medicare would be secondary to some Affordable Care Act option. It was just a myriad of concerns and not knowing," said the 72-year-old Roza, a retiree who lives in Oakdale, Calif., and is recovering from hip replacement surgery earlier this year.

He now knows that his Medicare coverage won't change, but says he's now worried about the impact on the $614 a month he pays for Medicare supplemental insurance. Federal health officials said seniors will not be able to purchase Medicare supplemental insurance or Part D drug plans through the state exchanges.

Jodi Reid, executive director of the California Alliance for Retired Americans, worries there hasn't been enough outreach to seniors and that advocacy groups are spending the bulk of their advertising funds targeting those impacted by the exchange. Her organization, which represents nearly 1 million seniors in California, is putting together a one-page fact sheet to help dispel myths.

"Nothing has been done that I have seen to deal with the 4.4 million people in California who are on Medicare who are not going to be impacted the same way as the rest of us so it's causing a lot of confusion," she said.

AARP officials said they anticipate a spike in calls after the October launch date for the new state exchanges. To help clarify everything for seniors, the organization is holding various events around the country, such as a senior day next month at the state fair in Columbia, S.C. Next month, the group is also hosting 21 telephone town halls, which will include hundreds of thousands of phone calls to seniors.

"Usually the marketing is just targeted to the Medicare beneficiary, this time it's going to be spread out a little bit more. If they call the wrong places, we're doing our very best to make sure they're guided back to the correct place," said Nicole Duritz, vice president of health education.

In Illinois, it's not only seniors who are confused, but also the social workers who help them, said Erin Weir of AgeOptions, suburban Cook County's lead agency on aging. The agency coordinates a statewide training program for groups that work with older adults.

During these trainings, Weir said, she's repeatedly heard questions from social workers who think seniors will be able to sign up for Medicare programs on the new marketplace websites, even though they cannot.

"We've been focusing on people who are already on Medicare, calming them down and saying, `You don't have to do anything, you're fine,'" Weir said.

Advocates are also warning of scams that may pop up alongside legitimate door-to-door outreach about the Affordable Care Act ramps up and advising seniors not to give out personal information.

Senior groups are also devoting resources to educating the 50- to 65-year-old group who are next in line for Medicare, a segment that could be greatly affected by the health reform. Under the new law, insurers will have to offer more benefits in some cases and are restricted in how much they can charge older, sicker people. They're also banned from turning away those with pre-existing conditions.

Anthony Wright, executive director of Health Access California, said many people nearing retirement age stand to benefit the most by the health care reform.

"They're the ones most likely to have pre-existing conditions, most likely to be charged more because of their age and medical condition and very likely to be an early retiree," he said.